Interrupts: Event-Driven Programming in ATmega Microcontrollers скачать в хорошем качестве

Interrupts: Event-Driven Programming in ATmega Microcontrollers

📥 RESOURCES & DOWNLOADS • Overview Interrupt Vector Table (IVT): https://drive.google.com/file/d/1dpLs... • Practical Examples: – Interrupt versus Polling: https://drive.google.com/drive/folder... – Interrupt Vector Table (IVT): https://drive.google.com/drive/folder... ✏️ EXERCISES • ATmega Sound: https://drive.google.com/drive/folder... 🧠 QUIZ https://forms.gle/98nqTbSZCbDnHcqo6 Have you ever wondered how embedded systems respond instantly to events without constantly checking for them? In this comprehensive section, we explore hardware interrupts - a fundamental concept that transforms how you write microcontroller code. You will learn how interrupts allow the CPU to react immediately to events while freeing it to execute other tasks, making your programs more efficient and responsive. We begin by comparing interrupts to polling, demonstrating why continuously checking register values wastes CPU resources and leads to timing inaccuracies. Through practical examples, you will see how the timer's interrupt request signals (OCnA, OCnB, TOVn) can notify your program when events occur, eliminating the need for constant polling loops. The section covers Interrupt Service Routines (ISRs) in depth: how to define them using the ISR() macro, how to derive interrupt vector names from the datasheet, and how to create aliases when multiple interrupts should execute the same code. You will learn about BADISR_vect for catching unexpected interrupts and EMPTY_INTERRUPT for defining placeholders. Interrupt activation is explained at both local and global levels. You will understand the Timer Mask registers (TIMSKn) for enabling specific timer interrupts, the Status Register's I-bit for global interrupt control, and the sei()/cli() functions for enabling and disabling interrupts atomically. We examine what happens when interrupts occur while global interrupts are disabled - they are deferred, but multiple occurrences of the same interrupt are not counted. The Interrupt Vector Table (IVT) is explored through practical disassembly, showing how the CPU jumps to fixed addresses when interrupts occur and how each entry contains a jump instruction to the corresponding ISR. You will see the relationship between word addresses in the datasheet and byte addresses in compiled code. The critical "volatile" keyword is explained with demonstrations showing how the compiler's optimizations can break interrupt-driven code by assuming variables never change outside normal program flow. You will understand when and why volatile must be used for variables shared between ISRs and the main code. External interrupts are covered comprehensively: Pin Change Interrupts (PCINTn) grouped into three banks, the PCMSK and PCICR registers, and techniques for determining which pin triggered a group interrupt. We also cover INT0/INT1 with their configurable edge detection (rising, falling, or any change) via the EICRA register. The section addresses interrupt priority (lower vector numbers = higher priority), nested interrupts using ISR_NOBLOCK, and the overhead of interrupt handling (storing program counter, jumping to IVT, executing ISR, returning via RETI). Best practices are emphasized: keep ISRs short, avoid delay functions and polling loops inside ISRs, and use interrupts instead of polling whenever possible. #Arduino #ATmega #Interrupts #ISR #InterruptServiceRoutine #Polling #EventDriven #EmbeddedSystems #Volatile #IVT #InterruptVectorTable #PinChangeInterrupt #PCINT #sei #cli #NestedInterrupts #RealTime 📖 CHAPTERS 0:00 Introduction 2:39 Polling versus Interrupts 4:18 Wait for Timer0 6:55 Practical Example: Implementing an Interrupt 15:03 Interrupt Subroutines (ISR) 18:56 How to activate Interrupts (sei/cli)? 21:57 The Interrupt Vector Table (IVT) 23:36 Practical Example: How does the Interrupt Vector Table (IVT) work? 29:48 Practical Example: What does the volatile keyword do? 34:25 Interrupt Sources 46:40 Priority of Interrupts 49:59 Nested Interrupts 51:28 Bad Coding Examples 53:21 Summary and What's next?